Blade holder for a snow-clearing device

ABSTRACT

The invention relates to a holder for connecting a blade ( 7 ) to the lower edge ( 6 ) of a snow-clearing device, such that the blade is given an acute, cutting angle to the base and can be folded backwards, thereby avoiding damage when running into an obstacle, and automatically resume its cutting angle after passing the obstacle. The holder comprises a trilateral hollow beam ( 1 ), the three sides of the beam forming respectively: a first fixing element ( 3 ) which is adapted to be fixed to the lower edge ( 6 ) of the snow-clearing device; a second fixing element ( 4 ) which is adapted to engage the back of the blade ( 7 ), and a support element ( 5 ) connecting the other two elements ( 3, 4 ). At least the second fixing element ( 4 ) and the support element ( 5 ) are made of an elastic polymer material. The hollow beam is adapted to fix the blade along a line along the lower part of the second fixing element ( 4 ) close to a corner of the beam, and the elastic elements ( 4, 5 ) are adapted, on overloading, to be buckled, the support element ( 5 ) being buckled towards the cavity ( 2 ) of the beam, and the second fixing element ( 4 ) being buckled forwards/upwards.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a holder for connecting a blade to the loweredge of a snow-clearing device, such that the blade is given a cutting(acute) angle to the base and can be folded backwards, thereby avoidingdamage when running into an obstacle, and automatically resume itscutting angle after passing the obstacle.

2. Description of the Related Art

In the first place, the invention is intended for use on a snow-clearingdevice comprising a plough wing, snow scraper or snow blade which issupported by a vehicle or device carrier of some type and which in itslower part has at least one blade serving to engage the ground with itscutting edge and ensure a snow-cutting and snow-raising action. Use isnormally made of a plurality of relatively short blades which aremounted side by side along the lower edge of the snow-clearing device.

It is desirable that the device can remove substantially all loose snowlying on a roadway, i.e. as far as possible also snow lying in cavitiesin the form of e.g. ruts in the roadway, to provide a safe base. Thismeans that the blades of the snow-clearing device must be able tooperate in close engagement with the roadway, which can be achieved ifthey are flexibly fixed to the lower part of the plough and thus can beindividually inclined in the lateral direction relative to the lowerpart of the plough. It is also desirable that the device can cut orscrape away snow or ice adhering to the roadway. Moreover, it should bepossible to carry out the above-mentioned snow-clearing work at highspeed. It goes without saying that snow-clearing under these conditionssubjects both the snow-clearing device and the device carrier to heavystress, and they can be damaged if the blade strikes against astationary obstacle, for instance, protruding gutters, kerbs, andrailway tracks.

To protect the device and the device carrier against damage arising incase of running into an obstacle, it is previously known to mount theblade to be pivotable backwards, against the action of a spring, about ahinge located above the blade. In this case, the blade must beessentially vertically oriented to the roadway, thereby making itpossible for the lower edge of the blade to move backwards/upwardswithout causing a lifting motion of the device. It is not possible toposition the blade at an evidently positive angle relative to thevertical plane, i.e. with the lower edge of the blade extended forwardsin the travelling direction. With this design, the blade thereforeoperates with a scraping effect against the roadway, thereby making itnecessary to press the blade against the roadway relatively firmly toensure good snow-clearing results. The construction also results in thesnow-throwing ability being limited.

A prior-art arrangement for protecting devices and device carriers whenthe blade is oriented at an acute, cutting angle to the roadway isdisclosed in International Patent Application WO 95/23894. The blade ishingedly attached to the front end of a forwardly extended pivot arm.When running into an obstacle, the blade can, against the action of aspring, be folded backwards while at the same time the pivot arm israised against the action of another spring. In this construction, theblade has a positive angle relative to the vertical plane and alsovertical flexibility relative to the roadway. However, a drawback is thefact that the blades cannot be inclined in the lateral direction and,thus, do not achieve the flexibility that is required to obtain a goodsnow-clearing effect on a rutted roadway. Besides, the mechanicalconstruction requires much repair and maintenance since it is subjectedto heavy wear and is easily damaged in this environment.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved bladeholder of the type mentioned by way of introduction, i.e. which isadapted to orient the blade at an acute, cutting angle to the roadwayand which has an automatic folding back effect when running into anobstacle. A further object is to provide a blade holder which under allsnow-clearing conditions gives the blades good flexibility and closeengagement with the roadway, i.e. also on roadways with ruts and ridges.One more object is to provide a simple, robust and light constructionwhich has no mechanical hinges. It should be possible to use the sametype of blade holder for all types of snow-clearing devices which areprovided with blades, e.g. front mounted ploughs, side wing ploughs,rear mounted ploughs, snow scrapers and blades mounted underneath, whichmakes it possible for the user of the device to simplify and standardisehis stock-keeping of wearing parts and spare parts.

These and other objects and advantages, which will appear from thefollowing specification, are achieved by a holder as defined in theclaims.

The inventive holder comprises a trilateral hollow beam, the three sidesof the beam forming respectively: a first fixing element (3) which isadapted to be fixed to the lower edge (6) of the snow-clearing device; asecond fixing element (4) which is adapted to engage the back of theblade (7), and a support element (5) connecting the other two elements(3, 4) to a triangular cross-section of the hollow beam (1), at leastthe second fixing element (4) and the support element (5) being made ofan elastic polymer material ensuring that each element, i.e. each sideof the hollow beam, is resilient in the transverse direction andbendable about its longitudinal direction; and means for attaching theblade to the hollow beam (1). The holder is characterised in that thehollow beam (1) has such a shape that, when mounted against the loweredge (6) of the device, the second fixing element (4) and the supportelement (5) are directed obliquely downwards/forwards and meet in acorner in front of the lower edge (6) of the device; that the hollowbeam is adapted to fix the blade along a line along the lower part ofthe second fixing element (4) close to said corner of the beam, thesecond fixing element (4) and the support element (5), in operation ofthe device, exerting on the blade a pressure spring action directedobliquely downwards/forwards, and that said elements (4, 5) are adapted,on overloading, to buckle, the support element (5) being adapted tobuckle towards the cavity (2) of the beam, and the second fixing element(4) being adapted to buckle forwards/upwards.

Preferably, the trilateral hollow beam has the same length as the bladethat has been chosen. Normally, each blade consists of a section of600-1800 mm, and a plurality of such sections are arranged side by sidealong the lower edge of the plough.

The invention is based on the idea of forming of a flexible material ablade holder which operates as pressure springs over the length of theblade and presses the blade in its direction of engagement against theroadway, thereby making it possible for the blade to follow the roadwayin the vertical direction and to be automatically inclined in thelateral direction for close engagement in ruts and on ridges in theroadway.

The blade holder orients the blade at an acute, cutting angle relativeto the roadway, which results in good clearing and snow-throwingability. The blade is folded backwards when striking against stationaryobstacles such as gutters, kerbs etc. and automatically resumes itsoperating position after passing the obstacle. This is achieved by thesecond fixing element and the support element being adapted to be folded(buckled) when subjected to an overloading pressure, such that the bladeis temporarily folded backwards and then is moved back to its operatingposition by the elasticity of the elements.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described in more detail withreference to the accompanying drawings.

FIG. 1 is a side view, in section, of a blade holder according to theinvention with a mounted blade and attached to the lower edge of aplough.

FIG. 2 shows the same blade holder subjected to load owing to frictionagainst the roadway.

FIG. 3 shows the same blade holder when the blade strikes against anobstacle.

FIG. 4 shows a plough wing with a plurality of juxtaposed blades.

FIG. 4a is an enlarged view of a blade in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

FIG. 1 thus shows a holder according to the invention, comprising atrilateral hollow beam 1 with an inner cavity 2, the three sides of thebeam forming: a first fixing element 3, a second fixing element 4 and asupport element 5, respectively.

The first fixing element 3 is fixed to the lower edge 6 of thesnow-clearing device. This edge is adjusted to the hollow beam to give asurface of attachment which is suitable in respect of size and angle,for instance, by a bent edge on the lowermost part of a plough blade.

At least the second fixing element 4 and the support element 5 are madeof an elastic polymer material which ensures that each element, i.e.hollow beam side, is resilient in the transverse direction and bendableabout its longitudinal direction. Many different types of elastomerswhich are resistant to loads are conceivable as polymer materials, e.g.urethane rubber or some other type of rubber material. Polyurethane is apreferred type of material.

The first fixing element 3 may consist of, for example, a steelsectional element, the other two elements being fixed to the steelsectional element so as to form a hollow beam. However, it is preferredto form the entire hollow beam in one piece of the same elastic polymermaterial, as shown in the Figures. It is particularly preferred to castthe hollow beam in e.g. urethane rubber. The urethane rubber should thenhave a hardness of at least 50° Shore A and, in many applications,preferably at least 70° Shore A.

The second fixing element 4 acts as a mounting for a blade 7. This sideof the hollow beam thus engages the back of the blade and is in itslower part formed with holes 8 for detachable fixing of the blade. Theattachment line of the blade thus is relatively close to a corner of thehollow beam. The material between the attachment line of the blade andthe lower edge 6 of the device serves as pressure springs which aredistributed over the entire length of the blade and press the blade inits direction of engagement against the roadway. The attachment of theblade can be effected in a conventional manner by means of, forinstance, a key and a key bolt, and the blade may be of a reversibletype with pairs of fixing holes 9 and 10.

To avoid cracking around the holes 8, the second fixing element 4 isprovided with a reinforcing steel bar 11, which is embedded in theelastic polymer material and extends along the element 4 in the area ofattachment of the blade in the hollow beam.

The third side of the hollow beam, the support element 5, connects theother two elements to a triangular cross-section of the hollow beam andacts as a spring holding the blade in place when affected by thefriction against the roadway, and also when the blade is inclined in thelateral direction, as described in connection with FIGS. 4 and 4a.

The blade holder 1 can be fixed to the lower edge of the snow-clearingdevice by means e.g. bolt joints. When the first fixing element 3 ismade of a polymer material, a reinforcing steel bar 12 is arranged onthe back of the fixing element in the cavity 2 of the beam. In theembodiment shown in the Figures, the steel bar 12 has a downwardly bentportion 13 along its one long side. The portion 13 extends a distancealong the back of the adjoining second fixing element 4 and serves tostabilise this element and control the direction of buckling, asdescribed in connection with FIG. 3.

FIG. 2 shows the behaviour of the blade holder during operation of thesnow-clearing device. When clearing snow, friction develops between theblade and the roadway and the blade is pressed slightly backwards. Thesupport element 5 acts as a spring and is compressed, and the motionmakes it slightly curved upwards towards the cavity 2 of the beam. Thiscurvature controls the direction of the buckling that is to happen whenthe blade strikes against an obstacle which may cause damage to thedevice and the device holder.

FIG. 3 shows the situation in which the blade strikes against anobstacle. The support element 5 will then be buckled upwards while atthe same time the fixing element 4 is buckled forwards/upwards owing tothe upwardly directed force generated by the blade when being raisedvertically. The motion is reinforced by a turning moment forming aroundthe attachment line of the blade at the steel bar 11. The blade achievesa dragging angle. After passing the obstacle, the blade holder springsback to its operating position.

FIG. 4 is a schematic view of a plough blade 14, to the lower edge ofwhich a number of blades 7 are mounted side by side. Each blade can bemounted with a blade holder which has a length corresponding to thelength of the blade. In the operating position, the blades should have apressure of engagement against the roadway to allow efficient clearingof snow. This means that the second fixing element 4 is compressed whileat the same time the support element 5 is compressed owing to thefriction when advancing the device. The force which thus is built up inthe elements 4 and 5 will incline the blade in the lateral direction asshown in FIG. 4a if the roadway has ruts or ridges.

The good flexibility of the blades against the roadway increases theclearing effect and means that the blades require but a small pressureagainst the roadway to achieve satisfactory engagement, which in turnreduces blade wear and power consumption in the snow-clearing work. Thesimple and robust construction minimises repairs and maintenance, andthe low weight reduces the weight of the device, which is of specialimportance to front mounted ploughs which are to be transported in anuplifted position and thus load the front axle of the device carrier.The flexible fixing of the blades also reduces noise and vibrations,which, inter alia, creates a better working environment for the driverand reduces damage to the device and the device holder owing tovibrations.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. A snow-clearing device having a lower edgedisposed above a ground surface when operating the device, a blademounted to said lower edge at an acute, cutting angle to the ground, anda holder connecting said blade to said lower edge such that said bladecan be folded backwards, thereby avoiding damage when running into anobstacle, and automatically resume its cutting angle after passing theobstacle, said holder comprising a trilateral hollow beam having threesides defining a central cavity, said three sides of the beam formingrespectively: a first fixing element which is fixed to said lower edgeof the snow-clearing device; a second fixing element which engages aback of the blade; and a support element connecting the first fixingelement and the second fixing element to a triangular cross-section ofthe beam said second fixing element and said support element being madeof an elastic polymer material ensuring that said second fixing elementand said support element are each resilient in a transverse directionand bendable about a longitudinal directione, said hollow beam havingsuch a shape that, when mounted against the lower edge of the device,the second fixing element and the support element are directed obliquelydownwards and forwards and meet in a corner in front of the lower edgeof the device, said blade being fixed to said beam along a line along alower part of said second fixing element close to said corner of thebeam, said second fixing element and said support element, in operationof the device, exerting on the blade a pressure spring action directedobliquely downwards and forwards, said second fixing element and saidsupport element buckling in response to overloading, said supportelement buckling towards the cavity of the beam, and said second fixingelement buckling forwards and upwards.
 2. The snow-clearing device ofclaim 1, wherein the blade is attached to said second fixing element bya steel bar which is arranged along the lower part of the second fixingelement.
 3. The snow-clearing device of claim 2, wherein said steel baris embedded in the elastic polymer material.
 4. The snow-clearing deviceof claim 1, wherein said first fixing element includes a steel sectionalelement, to which the second fixing element and the support element arefixed.
 5. The snow-clearing device of claim 1, wherein said hollow beamin its entirety is made of the elastic polymer material.
 6. Thesnow-clearing device of claim 5, wherein said holder further comprises areinforcing steel bar arranged on an inner edge of the first fixingelement in the cavity of the beam.
 7. The snow-clearing device of claim6, wherein said reinforcing steel bar along one side has a downwardlybent portion, which extends a distance along an inner edge of theadjoining second fixing element.
 8. The snow-clearing device of claim 1,wherein said elastic polymer material is a polyurethane.
 9. Thesnow-clearing device of claim 8, wherein said elastic polymer materialis a urethane rubber with a hardness of at least 50° Shore A.
 10. Thesnow-clearing device of claim 9, wherein said urethane rubber has ahardness of at least 70° Shore A.
 11. The combination of a blade and aholder for connecting said blade to a snow-clearing device having alower edge disposed above a ground surface when operating the device,said blade mounted to said lower edge at an acute, cutting angle to theground, and said holder connecting said blade to said lower edge suchthat said blade, when running into an obstacle, can pivot backward andflex upward to avoid damage thereto, and automatically resume itscutting angle after clearing the obstacle, said holder comprising atrilateral structure with three sides defining a central cavity, saidthree sides including a first fixing element fixed to said lower edge ofthe device, a second fixing element which engages the blade, and asupport element connecting the first fixing element and the secondfixing element, said second fixing element and said support elementbeing directed obliquely downwards and forwards and meeting in a cornerin front of the lower edge of the device, said blade being fixed to saidsecond fixing element along only an attachment line close to saidcorner, each of said second fixing element and said support elementbeing made of an elastic polymer material such that each is resilient ina transverse direction and bendable along a longitudinal edge, saidsecond fixing element and said support element exerting on the blade apressure spring-action directed obliquely downwards and forwards duringoperation of the device and, in response to overloading of the blade,buckling such that a respective longitudinal edge of said supportelement buckles upward into the central cavity of said trilateralstructure, and a respective longitudinal edge of said second fixingelement buckles forward and upward, said blade pivoting along theattachment line and moving upward with said attachment line withoutupward movement of the lower edge of the device.
 12. The snow-clearingdevice of claim 11, wherein the blade is attached to said second fixingelement by a steel bar which is arranged along a lower part of thesecond fixing element close to said corner.
 13. The snow-clearing deviceof claim 12, wherein said steel bar is embedded in the elastic polymermaterial.
 14. The snow-clearing device of claim 11, wherein said firstfixing element is a steel sectional element, to which the second fixingelement and the support element are fixed.
 15. The snow-clearing deviceof claim 11, wherein all three sides of said holder are made of theelastic polymer material.
 16. The snow-clearing device of claim 15,wherein said elastic polymer material is a polyurethane.
 17. Thesnow-clearing device of claim 16, wherein said elastic polymer materialis a urethane rubber with a hardness of at least 50° Shore A.
 18. Thesnow-clearing device of claim 15, wherein said holder further comprisesa reinforcing steel bar arranged on an inner edge of the first fixingelement along the cavity.
 19. The snow-clearing device of claim 18,wherein said reinforcing steel bar has along one side a downwardly bentportion, which extends a distance along an inner edge of the adjoiningsecond fixing element.
 20. A snow-clearing device having a lower edgedisposed above a ground surface when operating the device, a blademounted to said lower edge at an acute, cutting angle to the ground, anda holder connecting said blade to said lower edge such that said blade,when running into an obstacle, can pivot backward and flex upward toavoid damage thereto, and automatically resume its cutting angle afterclearing the obstacle, said holder comprising a trilateral structurewith three sides defining a central cavity, said three sides including afirst fixing element fixed to said lower edge of the snow-clearingdevice, a second fixing element which engages the blade, and a supportelement connecting the first fixing element and the second fixingelement, said second fixing element and said support element beingdirected obliquely downwards and forwards and meeting in a corner infront of the lower edge of the device, said blade being fixed to saidsecond fixing element only along an attachment line close to saidcorner, each of said second fixing element and said support elementbeing made of an elastic polymer material such that each is resilient ina transverse direction and bendable along a longitudinal edge, saidsecond fixing element and said support element exerting on the blade apressure spring-action directed obliquely downwards and forwards duringoperation of the device and, in response to overloading of the blade,buckling such that a respective longitudinal edge of said supportelement buckles toward the central cavity, and a respective longitudinaledge of said second fixing element buckles forward and upward, allowingthe blade to pivot along the attachment line and move upward with saidattachment line without upward movement of the lower edge of the device.